Thyratron control circuit



Aug. 4,' 1959 J. RYWAK 2,898,515

THYRATRON CONTROL CIRCUIT CONDITION/1V6 I/OLTA s:

F/anvs 46472165:

Filed March 9, 1959 4 I Ewe/13w Jomv RYWAK 2,898,515 Patented Aug 4THYRATRON CONTROL CIRCUIT John Rywak, Belleville, Ontario, Canada,assignor to Northern Electric Company, Limited, Montreal, Quebec,Canada, a corporation of Canada Application March 9,1959, Serial No.798,112

' 4 Claims. or. 315-168) ing two control grids, one of which is biasedsufiiciently negative with respect to the cathode of the tube so that apositive potential of predetermined magnitude, applied to the firinggrid, is unable to trigger the tube. In the normal operation, the firingpoint of the thyra- 2 i. in"

lector resistor 19 connected to the junction 'point 20. The resistanceof resistor 16 should be larger than the resistance of resistors 17 and19.

A unilateral conducting element, generally shown by the numeral 21 andhaving cathode 22, anode '23, is connected between the junction points11 and 18, while a unilateral conducting element, generally shown by thenumeral 24' and having cathode 25, anode 26, is connected between thejunction point '18 and the collector electrode 14 of transistor 12. Thenumerals 27, 28, 29, 30, 31, 32, 33, 34 indicate current limitingresistance elements. i

Fig. 2 illustrates a schematic circuit the same as shown in Fig. 1except that the thyratrontube 34 is a triode having a cathode 35,control grid 36 and anode 37; Q

In the operation of the circuit, in the non-operated or normalcondition, with transistor 6 in the non-conducting condition, thepotential at junction 11, as determined by the potential of collector 9of transistor 6 and the polarity of the biasing energy applied thereto,is at a negative potential with respect to the cathode 2 of thethyratron tube 1. Also the potential at the junction 18 is less negativethan the potential of cathode tron is determined by the effect of acontrolling'pulse placed on one or the other of the two grids, thevoltage of which is made sufiiciently large inorder to. assure theproper performance of the tube. However, when it is desired to controlthe firing of the thyratron by means of transistor circuitry, wherelarge voltages are not available, the problem becomes one of reliabilityof operation.

The principal object of this invention is to provide a control circuitfor a two grid thyratron tube by means of transistor circuitry.

Another object of this invention is to provide a control circuit for asingle grid thyratron tube by means of transistor circuitry. v

These and other objects of this invention are attained in one embodimentby providing a circuit arrangement, r

in association with a thyratron tube having a conditioning gridelectrode and control grid electrode, in which the bias on the grids iscontrolled by a pair of steering semiconductor elements, arrangedback-to-back, poled in the desired directions by the state ofenergization of a transistor individually connected to eachsemiconductor element. t ,I g

A better understanding of the invention may be had by referring to thefollowing description, taken in conjunction with the drawing in whichlike numbers refer to like parts in which:

Fig. 1 shows a schematic circuit of one embodiment of the inventionillustrating the circuit arrangement for the control of a two gridthyratron tube; and

Fig. 2. shows a schematic circuit of another embodiment of the inventionillustrating the circuit arrangement for the control of a single gridthyratron tube.

Considering Fig. 1 of the drawings there is shown a thyratron tube,generally shown by the numeral 1, having a cathode 2, a control grid 3,a conditioning grid 4, anode 5, p-n-p transistor, generally shown by thenumeral 6, having an emitter electrode 7, base electrode 8, collectorelectrode 9, collector resistor 10 connected to the conditioning grid 4and collector electrode 8 at the junction point 11.

There is also shown a second p-n-p transistor, generallyvshown by thenumeral 12 having an emitter electrode 13, collector electrode 14, baseelectrode 15, a pair of resistors 16, 17 to which the control grid 3 isconnected at the junction predetermined point 18, a col 2, as determinedby the resistance relation between resistor 16 and resistor elements 17,19, unidirectional elements 21 and 24 thus conducting so that junction18 assumes the same potential as junction 11. Any accidental positivepulse originating at transistor 12 will not be received on control grid3 of the thyratron tube -1 since unidirectional element 24 would becomenon-conducting.

If now a negative voltage is applied to the base electrode'8 oftransistor 6 of this transistor 6 becomes conducting, a circuit beingcompleted through resistance element 10. Junction 11 thereforebecomesmore positive with respect to its previous potentiakandunilateral conducting element 21 becomes non-conducting. If now anegative pulse is applied to thebase electrode 15 of transistor 12, acircuit is completed through resistance element 19 so that the collector14 of transistor 12 reaches ground potential and unilateral conductingelement 24 applies a positive bias to the control grid, 3 of thyratrontube 1 through resistance element '16, the tube 1 triggering. The grids3 and 4 now lose control of the triggering of the tube, the controlreturning themto by reducing the plate voltage or by other wellknownmeans.

tothe polarity of the energy sources, the polarity of the junction 18 isslightly at a negative potential as determined by the resistors 16 and17 and 19, with respect to the cathode 2 of the thyratron tube 34, sothat unilateral conducting element 21 conducts. If now a negativevoltage is applied to the base 8 of transistor 6, this transistor 6becomes conducting so that the cathode 22 of unilateral conductingelement 21 assumes a more positive potential than anode 23 and theunilateral conducting element 21 therefore becomes non-conducting sothat junction 18 assumes a potential as determined by resistors 16, 17and 19. If now a negative pulse is applied to the base electrode 15 oftransistor 12 this transistor 12 conducts completing a circuit throughresistors 19 so that junction, point 18 and control grid 36 assumes apositive potential with respect to the cathode 2 of thyratron tube 34,as determined by the resistor 16, the tube 34 triggering. Control grid36 loses control of tube 34, the control being returned by reducing theplate voltage or by other well known means.

Purely by the way of example and in a no limiting sense, suitable valuesfor the resistors used in connection with this circuit are:

It is to be understood that the above embodiment is by the way ofillustration only, there being other embodiments, in which difierenttypes of transistors may be employed.

What is claimed is:

1. An electron circuit arrangement employing a gas filled electronicdischarge tube having a cathode, a conditioning grid, a control grid,and an anode having in combination with the discharge tube: a firstp-n-p transistor having an emitter, a collector and a base electrode, afirst collector resistor, means for connecting the collector resistorand the conditioning grid to a first predetermined point on thecollector electrode; a first source of direct current having itsnegative terminal connected, through the collector resistor, to thefirst predetermined point and its positive terminal to the emitterelectrode; a second p-n-p transistor having an emitter, a collector anda base electrode, a pair of resistors connected in series relation, thecontrol grid being connected to a second predetermined point; a secondcollector resistor, means for connecting the second collector resistorand a free terminal of the pair of resistors to a third predeterminedpoint on the collector electrode of the second transistor; a secondsource of direct current having its negative terminal, through thesecond collector resistor, connected to the third predetermined pointand its positive terminal connected to other free terminal of the pairof resistors; an unilateral element individually disposed between thefirst and second predetermined points, with its cathode and anodeconnected to these points respectively, and between the pair ofresistors with its anode and its cathode, through the resistor of thepair thereat, connected to the second and third predetermined pointsrespectively; means for rendering the transistors conductive.

2. An electric circuit in accordance with claim 1 in which saidunilateral conducting elements comprise semiconductor diodes.

3. An electron circuit arrangement employing a gas filled electronicdischarge tube having a cathode, a control grid and an anode having incombination with the discharge tube: a first p-n-p transistor having anemitter, a collector and a base electrode, a first collector resistorconnected to a first predetermined point on the collector electrode; afirst source of direct current having its negative terminal connected,through the collector resistor, to the first predetermined point and itspositive terminal to the emitter electrode; a second p-n-p transistorhaving an emitter, collector and base electrode, a pair of resistorsconnected in series relation the control grid being connected to asecond predetermined point thereon, a second collector resistor,'meansfor connecting the second collector resistor and a free terminal of thepair of resistors to a third predetermined point on the collectorelectrode of the second transistor; a second source of direct currenthaving its negative terminal connected, through the second collectorresistor to the third predetermined point and its positive terminalconnected to the other free terminal of the pair of resistors; anunilateral element individually disposed between the first and secondpredetermined points, with its cathode and anode connected to thesepoints respectively and between the pair of resistors with its anode andits cathode, through the collector resistor, connected to the second andthird predetermined points respectively; means to render the transistorsconductive.

4. An electron circuit arrangement employing a gas filled electronicdischarge tube having a cathode, a conditioning grid, a control grid andan anode having in combination with the discharge tube: a first p-n-ptransistor having an emitter, collector and base electrode, a firstcollector resistor, means for connecting the collector resistor and theconditioning grid to a first predetermined point on the collectorelectrode; a first source of direct current having its negative terminalconnected, through the collector resistor, to the first predeterminedpoint and the positive terminal to the emitter electrode; a second p-n-ptransistor having an emitter, collector and base electrode, a pair oftransistors connected in series relation, the control electrode beingconnected to a second predetermined point thereon; a second collectorresistor,

means for connecting the second collector resistor and a free terminalof the pair of resistors to a third predetermined point on the collectorelectrode of the second transistor; a second direct current sourcehaving its negative terminal, through the second collector resistor,connected to the third predetermined point and its positive'terminalconnected to the other free terminal of the pair of resistors, anunilateral element connected between the first and second predeterminedpoints, with its cathode and anode connected to these pointsrespectively; means for rendering the transistors conductive.

No references cited.

